greasing up stern tube

[chaldon3]

just wondering what the function of the grease in stern tube does, i take it the packing prevents water ingress in to hull but what is the function of the grease.
garry

 

[superheat6k]

it lubricates and seals the packing material.

 

[omega2]

Stops fires in the stuffing box why else would you lubricate anything???

 

[chaldon3]

arrr right thanks guys my first inboard, i take it i just guesstimate the first fill then top up after every use,

 

[superheat6k]

Erm - do you have wind down greaser ?

If so you don't want to empty the entire pot each time - just a brief tweak of the winding handle once each sailing day until the resistance becomes firm. I would expect a fill will last months.

 

[Neil_Y]

A very good question, many thousands of boats with stuffing boxes don't have grease. I think it was a bright idea to prevent a poorly adjusted stuffing box from dripping when you leave the boat. Squeeze a turn in when you leave the boat is what I was taught. A conventional stuffing box works perfectly well with no grease, drips a bit when turning but properly adjusted should not drip when the shaft isn't turning.

The problem with grease is, it is a poor conductor of heat, water is a great lubricant and coolant so plain water systems run cooler.

Too much grease squeezed in at the top of the stern tube can make its way down to the shaft bearing, it can then prevent water lubricating and cooling the bearing and the bearing will wear out quickly. So don't get carried away with squeezing lots of grease in.

 

[chaldon3]

thank you very much guys for your valuable advice, basic questions i am sure but i have only ever had outboards. kind regards garry.